Thermal conductivity of water base Ni-np@MWCNT magnetic nanofluid

• Thermal conductivity properties of Ni-np@MWCNT nanofluids were performed in the presence and absence of a magnetic field. • The effects of changes in some parameters such as weight percentage, base fluid temperature and magnetic field strength on the thermal conductivity properties were investigated. • The thermal conductivity increases with increasing concentration of MWCNT nanoparticles within the nanofluid. • The presence of Ni@MWCNT nanoparticles significantly increases the thermal conductivity relative to MWCNT nanofluids as the relative growth rate of the thermal conductivity can be increased up to 16%. • Thermal conductivity increases significantly under the influence of the temperature increasing of the base nanofluid. • With applying magnetic field, the coefficient of thermal conductivity increases, however this increase depends on the concentration of Ni-np@MWCNT nanoparticles. Thermal conductivity behavior of a nanofluid constructed from encapsulated nickel nanoparticles inside multiwall carbon nanotubes (Ni-np@MWCNT) under various conditions of weight percentage, base fluid temperature as well as external magnetic field was studied experimentally. Ni-np@MWCNT nanoparticles were made by chemical process and various analyses such as XRD, VSM and TEM were implemented for characterizing their properties. The thermal conductivity of Ni-np@MWCNT nanofluid at different conditions of the nanoparticles weight percentage was surveyed as we found that there is an almost regular relevance between the increase in thermal conductivity and the concentration of nanoparticles of the nanofluid. We also investigated the role of nanofluid temperature as an effective parameter in thermal conductivity as we found a relative growth of thermal conductivity in all considered samples with increasing temperature. The results also show that the magnetic field can dramatically control the thermal conductivity of Ni-np@MWCNT nanofluids. The outcomes obtained in this work can be used to produce smart devices based on magnetic nanofluids. Thermal conductivity of Ni-np@MWCNT nanofluids at different weight percent.